Proc. Amer. Acad. Arts3: 184. 1855
w North America, nw Mexico.
Alsia is strikingly similar to Forsstroemia trichomitria, but the two taxa are completely distinct geographically. Alsia is endemic to the west coast of North America, while F. trichomitria is broadly distributed in eastern North America, occurring no further west than Oklahoma. The stems of Alsia are densely invested with paraphyllia, while paraphyllia are absent in F. trichomitria.